Stretch-forming machine



April 7, 954 L. R. GRAY ET AL 2,676,639

STRETCH-FORMING MACHINE Original Filed Sept. 2, 1950 3 Sheets-Sheet l 3nventors LANDO/V A. GRAY HA m Y P, SM/TH, m.

Gttomeg April 27, 1954 1.. R. GRAY ET AL STRETCH-FORMING MACHINE 5 Sheets-Sheet 2 Original Filed Sept. 2.

' Zmnentors LANDON A. GRAY HAAA) P. j'M/f/vf JR.

(Ittorneg 3 Sheets-Sheet 3 Srmentor! AAA/DON R. GRAY (Ittomeg April 27, 1954 I L R. GRAY ET AL STRETCH-FORMING MACHINE Original Filed Sept. 2

HARE) P J'M/TH, JR.

Patented Apr. 27, 1954 STRETCH-FORMING MACHINE Landon B. Gray, Manhattan Beach, and Harry P. Smith, Jr., Los Angeles, Calif, assignors to Richard Seifried, Playa del Rey, Calif.

Original application September 2, 1950, Serial No. 182,928, now Patent No. 2,632,493, dated March 24, 1953. Divided and this application December 15, 1952, Serial No. 326,098

3 Claims. 1

. This invention relates to a machine for forming bends in sheets while simultaneously stretching the sheets so that the same retain the bent form imparted by the machine. This application is a division of application Serial No. 182,928, filed September 2, 1950, issued March 24, 1953, as Patent No. 2,632,493.

A general object of the invention is to provide an improved stretch-forming machine that is particularly adapted to handle relatively large metal sheets with great efficacy.

Another object of the invention is to provide a machine of the character indicated that is more particularly adapted to stretch-form relatively wide sheets by forming them over a die of varying contour to impart more stretch to some parts of a sheet than to other parts, and to provide a novel arrangement of operating parts that enables forming a fiat sheet to one that is wholly bent upon itself, i. e., with the opposite edges of the sheet parallel in their general planes.

A further object of the invention is to provide a machine, as indicated, having a fixed frame and swingable arms pivoted thereto and to so form said frame and arms that the stress forces resulting from application of power to stretch and form a sheet are substantially uniformly absorbed by said base and arms, the same resulting in improved accuracy of a stretch-formin operation.

A still further object of the invention is to provide, in a machine as indicated, novel, improved and powerful means to effect stretchforming movement of the swingable arms, the

same, at the same time, being extremely sensitive in its operation. b 1

The invention also has for its objects to provide such means that are positive in operation, convenient in use, easily installed in a working position and easily disconnected therefrom, eco- 9 nomical of manufacture, relatively simple," and of general superiority and serviceability.

The invention also comprises novel details of construction and novel combinations and arrangements of parts, which will more fully appear in the course of the following description. However, the drawings merely show and the following description merely describes one embodiment of the present invention which is given by way of illustration or example only.

In the drawings, like reference characters designate similar parts in the several views.

Fig. 1 is a plan view of a stretch-forming machine embodying the improvements of the present invention.

Fig. 2 is an enlarged front elevational view thereof showing the two sheet-bending arms in two different positions.

Fig. 3- is an end view as seen from the left of Fig. 2.

Fig. 4 is a plan sectional view on the plane of line 4'4 of Fig. 2, the same showing the left side of the machine, the right side being similar.

The machine that is illustrated comprises, generally, an elongated rigid base frame 5; an adjustable die box assembly 6 carried by said frame; a pair of swingable arm assemblies 1!, one on each side of the base frame, a pair of hydraulic cylinder assemblies 8 connecting the base frame 5 and the free ends of each arm assembly to swing the latter between an aligned position and a position substantially parallel to said base frame; and a tension cylinder assembly 9 carried by each arm assembly and each having a sheetgripping jaw l0, said jaws cooperating to hold a sheet II in position to be stretched and formed over a die [2 mounted on the die box'assembly t.

The base frame 5 may be variously made. As

shown, the same comprises a fabricated structure of welded metal plates. Said base frame 5, as seen in Fig. 3, is generally c-shaped and comprises horizontally disposedbase and cap portions Band [4, respectively, connected at their rearward ends by a vertical column l5 through the medium of transverse bolts [6. In this manner the base frame is provided with a front open space H in which die block assembly 6 resides. The -c-shaped and elongated frame thus provided is rendered stable by laterally directed foot brackets [8 at the front and rear of base portion l3, the same affording means by which the frame may be bolted to a supporting surface. Frame 5' is formed to have parallel sides l9 and, extending laterally from said sides, the base and cap portions l3'and M of the frame are each providd'withbracket bearings 20, as'best seen in Fig. 2. Said bearings are shown at the front of the "frame and are arranged as opposed pairs above and below frame opening I1.

The upper face 2| of base portion 13 and the opposite under face 22 of cap portion [4 are each provided with a series of transverse and aligned key slots 23 that are utilized to locate die block assembly 2! relative to the open front of the frame. Said frame portions on each side, are each provided with bearings 25 for pivotal connection with one end of each of the hydraulic cylinder-assemblies 8. Bearings Mare provided intermediate the front and rearof said frame portions.-'

Die box assembly 6 is slidingly fitted in space ll between faces 2! and 22. The same comprises a box 25 on the front of which is affixed a vertical wall 26 on which die 12 is remcvably mounted; A platform 21 extends forward. from the die" box and serves as a support for spacers 28 on which the die rests. The thickness of said spacers varies according to the height and verti-- cal disposition of the die in space M. It will. be understood that the die I2 is adjustably positioned in space H relative to the open end of the. frame and is located and' held as by means of keys 29 in a selected aligned pair of key slots 23'. Said keys 29 may be projected into; or retracted from said slots by means 30" which form. no part of the present invention.

Each of the two arm assemblies i=- isformed' as a generally C-shaped frame as best seen. in. Fig. 2. Each said assembly comprises upper and lower horizontally disposed arms 3! that are each provided with ears 32- arranged in pairs and connected tobearings 2t b-y' pivot pins 33. In this manner, the arms 3i are generally horizontally aligned with the base and cap portions l3 and M of frame 5. Therefore, the space 34, defined between arms ill of each arm assembly, isgenerally aligned with space" H in the base frame. Also, in the present case, the upper face 35 of each lower arm is arranged to horizontally align with the upper face 2!" of base portion l3, and under face 35 of each upper arm is similarly aligned with the under face 22 of cap portion M Key slots 31', comparable to key slots 23, are provided in faces 35 and 36.

The outer free ends of each pair arms are each provided witha forwardly onset portion 38 and the same are connected by vertical members 39. To render rigid the portions 38 and. member 39' of each arm, the latter, at its upper and: lower end, is connected by a brace 413 to each respective arm 31 adjacent ears 32 of said arms; In this manner',.each arrrr assembly I.- has a triangur la-r form as seen in plan, and comprises a rigid C-shaped frame structure in which? the vertical component 39 is forwardly olfset providing: a clear space in which tension cylinder assembly 9 is adapted to operate.

The vertical members 39. are each extended above and below the correspondingarms 3!. and each said extension M mounts a. pivot 4'2 for the outer ends of hydraulic cylinder assemblies 8.

Said assemblies 8 each comprises a cylinder 43 on pivot 24 and a piston in said cylinder and having a stem 4-4 connected to pivot 42 As will be seen, thereare four such assemblies 8",. two for each arm assembly l, one above and onebelow the arms 3t of each of said arm assembly. Inasmuch as pivots 24 are on. one side of. pivots 33 and pivots 42 are on the opposite side; said cylinder assemblies 8 extend. angularly' relative tothe general disposition. of arm assemblies 1:, i. e'.,, said cylinder assemblies extend angularly across the arms 3! and particularly across the plane common to pivots 33 and. the points of connection of tension cylinder assemblies and arm assemblies '5.

The cylinder assemblies 8 comprise extensible and contractable devices which, inthis case, are hydraulically operated to provide power for swinging assemblies 7. It will be clear (see Fig. 4) without the need for detailed description that pressure fluid may be conducted to each cylinder 43:, as at 4 5, to cause extension of stem ill and at Ali to cause retraction of said stem, thereby changing the effective length of said assemblies. When said cylinder assemblies are extended, the arm assemblies 1 are outwardly extended on pivots 33. By contracting the cylinder assemblies, said arm assemblies can be swung rearward until they are disposed against and parallel to frame sides it and are parallel to each other, as shown by the dot-dash lines of Fig. 1. This position represents maximum retraction of the arm assemblies. Of course, any intermediate retracted position may be had, as illustrated in Fig. 4.

The details of' the tension cylinder assemblies 8 are not important in this case, since the same are fully disclosed in the mentioned application of which this application is a division. Generally, each said tension cylinder assembly comprises a housing 47!; a jaw-supporting tube it extending horizontally through said housing; a clevis 49 on that end of said tube that is directed toward the open end of the arm assembly mounting: saidv tension: cylinder assembly; transverse pivot: 50 in said clevi's; a; sheet gripping jaw 10 on said. pivot: and generally vertically disposed; means comprising two similar cylinder assemblies. 52,. also extending through housing. ll, and responsive to greater resistance to movement of one end of the jaw than of the other, to stabilize said jaw on its pivot 5!) and to hold said jaw in such stabilized position subsequent tov any oscillation thereof on said pivot; a yoke 53' interconnecting assemblies 52' and tube 48 and disposed outward of housing l'l; means comprising cylinder assemblies 54', out of yoke 53, interconnecting said tube and cylinder assemblies 52 and responsive to unequal forces on the jaw on opposite sides of pivot 48 that tend to rotate said jaw on the axis of thetube 5- to stabilize said jaw subsequent to any rotation thereof: on said axis; and a pair of brackets 55. adjustable on and along arms 3 l and pivotally mounting housing ll. The latter pivot is best shown at 55 in Fig- 4-. Brackets 55 are held in adjusted position by keys 51 in a selected pair of aligned slots 31 of arms 3i.

The cylinder assemblies 52 are operated by hydraulic fluid to retract or project tube 48- and jaw l0 thereon in the space 35. It will be clear, therefore, that a sheet 1- 1, having its ends gripped by jaws iii and spanning across the front of die I2, is adapted: to be stretched by retraction of one or both tension cylinder assemblies 5i as above generally described, and that said jaws are free to pivot with said assemblies 9 on pivots 56 during swinging of the arm assemblies as also described above. Such pivotal. movement of assemblies 9' may be effected and controlled by means of a cylinder piston unit 53 extending betweenv each lower bracket 55 and extension 55 on. each; housingv 41.

It will. be seen. from the foregoing that the stretch-forming machine provided. comprises three C-shaped frames of which one is fixed and the other two are-swingable relative thereto; that said three frames are so arranged relatively that the openings or spaces between their horizontal arms combine to create a clear space in which the tension cylinder assemblies 9, the die 12, and the sheet ii that is formed around said die, are disposed; that the die is effectively supported by the arms of the fixed frame which receive the forces imparted to the.- die during the machine operation; and that the arms of the swinging frames serve. ina similar capacity to take the forces generated in the; tension cylinder assercblies. Therefore, the present machine is quite stable, well-balanced, and resistant to distortion by the stresses resulting from the forces generated.

While we have illustrated and described what we now contemplate to be the best mode of carrying out our invention, the construction is, of course, subject to modification without departing from the spirit and scope of the invention. It is, therefore, not desired to restrict the invention to the particular form of construction illustrated and'described, but to cover all modifications that may fall within the scope of the appended claims.

Having thus described our invention, What We claim and desire to secure by Letters Patent is:

1. A stretch-forming machine comprising a C- shaped base frame having upper and lower horizontal frame portions connected at the rear by a vertical portion to define a front-open space, horizontally adjustable means disposed in said space and adapted to mount a forwardly-facing die, a pair of bearing brackets carried by the for- Ward end of each horizontal frame portion, said pairs of brackets being arranged as opposed and aligned pairs on each side of the base frame, one above and one below said frame opening, agenerally C-shaped arm on each side of the base frame and comprising upper and lower horizontal portions and an end vertical portion connecting the horizontal portions at their ends and laterally offset from the general plane of said arm, pivots on the other ends of the arms connecting each said arm to the mentioned opposed and aligned pairs of bearing brackets, respectively, the mentioned oifset vertical portion of said arms, when said arms are aligned with each other on the mentioned pivots and extend in opposite directions from the base frame, being disposed forwardly of the open front of the base frame, two vertically aligned pairs of pivots in the horizontal portions of the base frame intermediate the forward open end of said frame and the rear vertical portion thereof, and a pair of upper and lower extensible and contractable devices extending in extensible condition from each pair of vertically aligned pivots in the intermediate portion of the base frame diagonally across each respective arm and pivotally connected to the vertical offset portion of each respective arm, said extensible and contractable devices being, thereby, disposed at a forward and outward angle when the arms are aligned and oppositely directed, said devices being fluid operated to contractand move the arms on their respective pairs of pivots from the mentioned aligned position to a position substantially parallel to the sides of thebase frame and to each other and wherein the offset vertical portions of the arms are in opposed relation to'each other, the contracted devices, in the latter position of the arms, extending from their pivots in the base frame at a rearward and outward angle diagonally across the substantially parallel arms, each arm mounting sheet-gripping and -tensicning means movable with the arms to bend a sheet spanning between the latter means around said die during movement of the arms from their aligned position toward their parallel position.

2. A stretch-forming machine according to claim 1 the end of each arm opposite the aligned pair of pivots thereof being open, and the sheetgripping and -tensioning means. extending, in part, through said opening and beyond the outer end of the arm.

3. A stretch-forming machine comprising a base provided with horizontal adjustable means mounting a forwardly facing die, the forward end of said base being provided with laterally directed bearing brackets, one on each side of the base, an arm pivotally connected by one end to each bearing bracket and each arm being provided with an offset portion at the opposite end thereof, said portions being offset forwardly of the forward end of the base when said arms are aligned on their pivots with each other andsubstantially at right angles to the base, a pair of pivots provided in the base intermediate the front and rear thereof, an extensible and contractable device extending from each of said pair of pivots diagonally across each respective arm and pivotally connected to the offset portion of each said respective arm, said devices, thereby, extending at a forward and outward angle with respect to the base when said arms are aligned as mentioned, said devices being in extended condition in the latter position of the arms, said devices being fluid operated to contract and move the arms on their respective pivots from the mentioned aligned position to a position substantially parallel to the sides of the base and to each other and wherein the offset portions of the arms are in opposed relation to each other, the contracted devices, in the latter position of the arms, extending from their pivots in the base at a rearward and outward angle diagonally across the substantially parallel arms, each arm mounting a sheet-gripping and -tensioning means movable with the arms, to bend a sheet spanning between the latter means around said die during movement of the arms from their aligned position toward their parallel position.

References Cited in the file of this patent "UNITED STATES PATENTS 

